The pair has regularly spoken to ASADA's investigators but are yet to sign official statements, saying they are under no obligation to do so and never said they would.

This latest development reportedly has ASADA concerned it has no case without the two witnesses and it intends to petition the Victorian Supreme Court for subpoenas compelling Charter and Alavi to appear at the hearing in mid-December, but even a court order would not force either to answer questions.

Charter has told ASADA he arranged for a batch of peptides to be imported from a Shanghai supplier in 2011.

According to Charter, the materials for the peptides were delivered to Alavi's pharmacy in Toorak in January the next year.

Alavi told the anti-doping agency a batch of Thymosin from China was delivered to his pharmacy and he compounded the peptide and gave it to controversial sports scientist Stephen Dank.

Charter has been charged with a number of unrelated drug-related offences, including trafficking steroids and possessing a schedule-four poison, after he was arrested by Purana Taskforce detectives at Melbourne Airport and interviewed in late May.

He is set to appear before the Melbourne Magistrate's Court on Wednesday.

If ASADA's case does fall apart, the Federal Government would face pressure to put together an inquiry into the authority's handling of the supplements saga.